1. Technical Field
The invention relates generally to capacitors and more specifically to capacitors formed with damascene technology.
2. Related Art
For damascene technology, many integrated circuit components, such as capacitors, are formed in openings or trenches that are etched into an insulator, formed on top of a substrate. A conventional method of manufacturing capacitors is through layering metal-insulator-metal (MIM). Specifically, for a damascene capacitor, the capacitor is formed by first depositing a first metal layer into a trench that was etched into the insulator. A capacitor dielectric layer is then deposited on top of the first metal layer, and then a second layer of metal is deposited over the capacitor dielectric. Thus, the MIM plates will cover the bottom of the trench and extend vertically along the sidewalls of the trench. A chemical mechanical polishing (CMP) process may then be used to planarize the capacitor with the surface of the insulator.
Problems may occur when forming this type of capacitor. Specifically, dielectric breakdown properties of the capacitor dielectric are degraded in some areas, and leakage and dielectric breakdown may occur between the capacitor plates.
Accordingly, a need exists for a damascene capacitor that will prevent leakage and dielectric breakdown between the capacitor plates and provide a more reliable capacitor used in damascene or similar technology.
The present invention provides a capacitor structure and method for making the capacitor that essentially eliminates leakage and dielectric breakdown between the capacitor plates of the capacitor structure, both on the surface of the trenches and in the bottom corners of the trenches. This is accomplished through the recessed capacitor plate of the present invention.
Generally, the present invention provides a metal-insulator-metal (MIM) capacitor device comprising:
a trench having sidewalls formed in a layer of interlevel dielectric insulator;
a first thin lower conductor plate formed in the bottom of said trench;
a second upper conductor plate coplanar with the surface of the interlevel dielectric insulator; and
a dielectric layer formed between said first conductor plate and said second conductor plate, said dielectric layer isolating one of said conductor plates from extending to said sidewalls of said trench and isolating at least one upper corner of said one of said conductor plates from extending towards the top of said trench.
In addition, the present invention provides a method of forming an MIM capacitor comprising the steps of:
a) forming a trench having sidewalls in a layer of interlevel dielectric insulator;
b) forming a first thin lower conductor plate in the bottom of said trench;
c) forming a dielectric layer on said lower conductor plate;
d) forming a second upper conductor plate on said dielectric layer and coplanar with the surface of the interlevel dielectric insulator; and
e) isolating at least one upper corner of one of said conductor plates from extending to said sidewalls of said trench and extending towards the top of said trench.
The present invention also provides a damascene system having an MIM capacitor device comprising:
a substrate;
a layer of interlevel dielectric insulator deposited on said substrate;
at least one trench having sidewalls formed in said layer of interlevel dielectric insulator;
a first thin lower conductor plate formed in the bottom of said trench;
a second upper conductor plate coplanar with the surface of the interlevel dielectric insulator;
at least one contact for contacting said lower or upper conductor plate; and
a dielectric layer formed between said first conductor plate and said second conductor plate, said dielectric layer isolating one of said conductor plates from extending to said sidewalls of said trench and isolating at least one upper corner of said one of said conductor plates from extending towards the top of said trench.
The foregoing and other features of the invention will be apparent from the following more particular description of embodiments of the invention, as illustrated in the accompanying drawings.